Excessive battery drain while sleeping after 10.13.4 update

My 2013 Macbook Air could always sleep overnight without losing more than a percent of battery life. But after the 10.13.4 High Sierra update, it started dropping to 78% or even less overnight if put to sleep by simply closing the lid. I measured the loss at about 6-8%/hour until it goes into "deep sleep" after the default 3 hours. I scoured the forums and tried most of the recommendations (reset SMC and pram, disabled Power Nap, etc.) except a complete reinstall of OS X. I finally discovered that if I turn off WiFi manually before sleeping, it only loses 0.6%/hour (10x less) or just a few percent until deep sleep overnight, still more than it did before but tolerable. I will adopt this add'l step before sleep until Apple fixes this obvious bug that they introduced with the 10.13.4 update.